Overhead conveyor pallet systems are well known within the manufacturing industry. Such overhead conveyor pallet systems commonly utilize a steel plate-like pallet having rollers mounted thereon that roll between a pair of overhead guide rails. The pallet typically has a steel fixture mounted thereon that hangs down from the pallet and is designed for hanging a workpiece from the steel fixture. Such workpieces may be rather large and heavy, and thus, the steel fixture must be relatively strong in order to support the weight of the workpiece. For example, in the automotive industry, such workpieces may include side body panels and fenders of automobiles. A chain-driven drive system engages the pallet and pulls the pallet and the workpiece along the guide rails, thereby transporting the workpiece from one location to the next.
The chain-driven drive system often includes a clutch drive on top of the pallet such that the pallet may engage and disengage the chain drive. By allowing the pallets to engage and disengage the chain drive, the workpieces can be idly stacked in a queue so that the workpieces may be delivered upon demand. For instance, a number of workpieces may be held in a queue, and when a worker or machine is ready to perform an operation on the workpiece, the clutch drive may engage the chain drive so as to pull the pallet and the workpiece to the desired location. Once the workpiece is removed from the pallet, the pallet may be pulled and guided along a 180° turn upward such that the pallet is turned upside down and driven back to the beginning of the conveyor. Upon reaching the opposite end of the conveyor, the pallet is guided along a 180° turn downward, such that the pallet is turned right-side-up, so that the pallet may be loaded with a new workpiece at the beginning of the conveyor.
Due to the weight of the steel fixtures hanging from the pallets, the chain drive and the clutch drive often malfunction. For instance, the clutch drive may not be able to engage and hold the chain drive under the weight of the pallet, and the weight of the pallets may also place too large of a load on the chain drive, thereby overloading the drive and affecting the speed and performance of the conveyor. The weight of the workpiece may also accentuate the problem. This problem is further accentuated through the rising of the conveyor along its path and the turning of the conveyor upside down to return the pallet to the beginning of the conveyor.